Project description:Background: Farm exposures in early life reduce the risks for childhood allergic diseases and asthma. There is less information about how farm exposures relate to respiratory illnesses and mucosal immune development. Objective: We hypothesized that children raised in farm environments have a lower incidence of viral illnesses over the first two years of life than non-farm children. We also analyzed between farm exposures or respiratory illnesses were related to patterns of nasal cell gene expression. Methods: The Wisconsin Infant Study Cohort (WISC) birth cohort enrolled farm and non-farm pregnant women from central Wisconsin. Parents reported prenatal farm and other environmental exposures. Illness frequency and severity were assessed using illness diaries and periodic surveys. Nasopharyngeal cell gene expression at age two years was compared to farm exposure and respiratory illness history. Results: There was a higher rate of respiratory illnesses in the non-farm vs. farm group (rate ratio 0.82 [0.69,0.97], p=0.020), but no significant differences in wheezing illnesses. There was a stepwise reduction in rates of respiratory illnesses in children exposed at least weekly to 0, 1, or ≥2 animals (p=0.006). In analyzing nasal cell gene expression, farm exposures and preceding respiratory illnesses were positively related to gene signatures for mononuclear cells and innate and antimicrobial responses. Conclusions: Children exposed to farms and farm animals had lower rates of respiratory illnesses over the first two years of life. Both farm exposures and preceding respiratory illnesses were associated with increased innate immune responses, suggesting that these exposures stimulate mucosal immune responses to reduce subsequent illness frequency.
Project description:To establish general differences between the protein expression in S. aureus strains, five methicillin sensitive S. aureus (MSSA) strains and five methicillin resistant S. aureus (MRSA) strains were compared both individually and as MSSA and MRSA groups in the absence of antibiotics. Proteins were compared by ultra-performance liquid chromatography-mass spectrometry.
Project description:Bacterial sepsis is a major killer in hospitalized patients. Coagulase-negative staphylococci (CNS) with the leading species Staphylococcus epidermidis are the most frequent causes of nosocomial sepsis, with most infectious isolates being methicillin resistant. However, which bacterial factors underlie the pathogenesis of CNS sepsis is unknown. While it has been commonly believed that invariant structures on the surface of CNS trigger sepsis by causing an over-reaction of the immune system, we show here that sepsis caused my methicillin-resistant S. epidermidis is to a large extent mediated by the methicillin resistance island-encoded peptide toxin, PSM-mec. PSM-mec contributed to bacterial survival in whole human blood and resistance to neutrophil-mediated killing, and caused significantly increased mortality and cytokine expression in a mouse sepsis model. Furthermore, we show that the PSM-mec peptide itself, rather than the regulatory RNA in which its gene is embedded, is responsible for the observed virulence phenotype. While toxins have never been clearly indicated in CNS infections, our study shows that an important type of infection caused by the predominant CNS species, S. epidermidis, is mediated to a large extent by a toxin. Of note, these findings suggest that CNS infections may be amenable to virulence-targeted drug development approaches. We used microarrays to detail the global gene expression between S. epidermidis strain Rp62A and S. epidermidis strain Rp62A isogenic Δpsm-mec deletion mutants
Project description:Methicillin-resistant Staphylococcus aureus is one of the major causative agents associated to infections with a high morbidity and mortality in hospitals worldwide. In previous studies, we reported that lignan 3'-demethoxy-6-O-demethylisoguaiacin isolated and characterized from Larrea tridentata showed the best activity towards methicillin-resistant S. aureus. Understanding of mechanism of action of drugs allows design drugs in a better way. Therefore, we employed microarray to obtain gene expression profile of methicillin-resistant S. aureus after exposure to 3'-demethoxy-6-O-demethylisoguaiacin. The results showed that lignan had an effect on cell membrane affecting proteins of the ATP-binding cassette (ABC) transport system causing bacteria death.
Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen in both community and health care settings, which causes a wide range of infections. Its resistance to β-lactam antibiotics and methicillin in particular, greatly complicates treatment options and success rate due to the limited number of antibiotics with activity against MRSA. To further the development of alternative therapeutics, the mechanisms that mediate antibiotic resistance in MRSA need to be fully understood. Cannabinoid compounds including cannabidiol (CBD), tetrahydrocannabinol (THC) and cannabinol (CBN) have shown promise as potential antibiotic adjuvants. In the present study, MRSA cells were subjected to antibiotic stress from methicillin in combination with three cannabinoid compounds, and subsequently analysed using metaproteomics to assess the metabolic response. Subjecting MRSA to methicillin made the cells more viable and increased their energy production, as well as upregulation of penicillin-binding protein 2 (PBP2). The cannabinoids all showed antimicrobial activity against MRSA, and inhibited the energy production of the cells as well as PBP2 when used in combination with methicillin. Furthermore, all three cannabinoid compounds inhibited resistance mechanisms in MRSA, resulting in a decrease in the minimum inhibitory concentration (MIC) of methicillin when used in combination.
Project description:Methicillin resistance in Staphylococcus aureus depends on the production of mecA, which encodes penicillin-binding protein 2A (PBP2A), an acquired peptidoglycan transpeptidase with reduced susceptibility to beta-lactam antibiotics. Here, we show that preventing the expression of wall teichoic acids (WTAs) genetically or with a TarO inhibitor sensitizes MRSA strains to beta-lactams although PBP2A is still expressed. Using S. aureus microarrays and array data analysis protocols (NIAID's Pathogen Functional Genomics Resource Center) we have characterized the transcriptomes of S. aureus COL. in order to further understand the sensitization of strain COL to methicillin by tunicamycin we determined the tunicamycin and methicillin transcriptomes alone and in combination. Methicillin treatment of COL at 500 µg/mL had almost no effect on cell growth rate and, remarkably, the only gene in the transcriptome that showed a more than two-fold change in expression was lytM, which was downregulated. The tunicamycin transcriptome of COL, acquired at 0.4 µg/mL, shows modest changes compared to the untreated control both in terms of the total numbers of affected genes and in the degree of up- or downregulation. Several of the genes upregulated upon tunicamycin treatment are part of the cell wall stress stimulon.COL was grown with methicillin to an OD600 ~0.4, and challenged with tunicamycin for 2 hrs whereas the control culture contained methicillin alone. transcriptome for COL growing in the presence of both agents showed extensive changes in gene expression. , the cell wall stress stimulon, which was not induced by methicillin when tunicamycin was absent, was clearly induced in its presence and the changes were far more dramatic than observed with tunicamycin alone. ). vraS and vraR, which encode a two component signaling system dedicated to the cell wall regulon, were upregulated 3.8 and 3.7 fold, respectively. Other upregulated cell wall stress stimulon genes include pbp2, fmtA, mvaD (mevalonate diphosphate decarboxylase), crtN (dehydrosqualene desaturase) mvak1 (mevalonate kinase), recU, SAV1424 (methionine sulfoxide reductase A), prsA (peptidyl-prolyl cis/trans isomerase), tcaA (Tca protein) and cwrA. A considerable number of genes were also downregulated upon challenge of COL with the combination of tunicamycin and methicillin. These included sspB, lrgA, dltA, capL, SAS0988, sspA, pflB, and spa. Several of these genes have been found to be downregulated in previous studies of cell wall-active antibiotic challenge of S. aureus.